Combine first 7 ingredients in a bowl and whisk until thoroughly
mixed. Taste, and adjust seasoning if necessary with more honey or
vinegar.

Place the steak in a large ziploc bag, and pour in the ponzu mixture.
Seal the bag and refrigerate for 4 hours or overnight.

When you're ready to cook, heat your grill (or broiler) to high.
While the grill is heating, remove the meat from the refrigerator and
let it come to room temperature. Cook for 4 minutes on each side,
brushing occasionally with the leftover marinade. Remove the meat from
the grill and allow it to sit, covered with a piece of aluminum foil,
for 10-15 minutes before slicing.